November 10, 2012

Investigating East Asian admixture in Balkans/Anatolia/Caucasus

I used ALDER with a dataset of populations from the Balkans, Anatolia, and Caucasus, using the She, Japanese, Miaozu, and Dai as East Asian references. A few caveats for this analysis:

Some populations may possess "South Asian" admixture which may be mistaken for East Asian

Populations differ in the number of SNPs used in the analysis; for example, the Armenian_D sample includes mostly Family Finder data which has a smaller overlap with the SNP set used

Populations differ in the number of individuals used, from a low of 5 (e.g., Turkish_Cypriot) to a high of 45 (Armenian_D)

I have also added the HGDP Europeans to the analysis. The results can be seen below; I have made bold those rows where all estimates are at least one standard error above zero, and bold/big those where the estimates are they are two standard errors above zero. I consider the latter to be the most reliable.

I have already discussed the Turkish signal of admixture at length elsewhere. I will note that the Iranian_D sample produces similar or younger admixture dates, which would make sense, given the fact that the Iranians came under control of the Mongols, while the successes of the latter in Anatolia were short-lived.

A very interesting signal is that of the North Ossetians which show admixture ~9-10 centuries ago. This seems to have occurred a little after the foundation of the kingdom of Alania, and I think it makes excellent sense to view it as the signal of Eurasian nomads (who must have carried some East Asian admixture at that time) intermingling with pre-Iranic local Caucasus populations, Two other populations from the Caucasus, the Georgians and Lezgins (and also the Abkhaz and Chechens) show earlier admixture signals that could very well date to the period of east-west Eurasian migrations inaugurated by the Huns, although a possible Sassanian origin of such influence cannot be overlooked.

The Kurds are another interesting case where the Dodecad sample and the Yunusbayev et al sample produce very different dates. The different number of SNPs may be at play here, or it may be that some Dodecad participants have recent Turkish ancestry that cause the admixture date average to appear lower, although the globe13 analysis suggests that the "East Asian" found here may be in fact "South Asian".

It seems to me that with large, dense, and well-curated sample sets from several of these populations, their admixture dynamics will become more distinct.

Georgians_D have extremely early admixture dates compared to the rest of the dataset, what do you think would be the explanation?

Also, would you be interested in performing a similar analysis to detect purely European admixture dates in West Asian/Caucasus populations? Besides Ossetians, the Chechens, who possess relatively high European admixture are also an interesting case.

Kurds_Y samples as far as I know are taken from diaspora Kurds in Kazakhstan whom originated in Azerbaijan and Northwest Iran and were deported there by Stalin. It is very likely that they did intermix with native Kazakh people.

It is interesting that Russians have more recent admixture times than other Slavs. Can it be taken as a proof of later Slavic colonization of the Russian plain? And also can ancient admixture time in French and Basques testify to Indo-European migrations?

Kurds_Y samples as far as I know are taken from diaspora Kurds in Kazakhstan whom originated in Azerbaijan and Northwest Iran and were deported there by Stalin. It is very likely that they did intermix with native Kazakh people.

There is nothing in the Kurds_Y samples that suggests they have any admixture from Kazakhstan. They just reside in Kazakhstan, but genetically have nothing to do with Kazakhstan. They are genetically typical Kurds.

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